Add lecture 5 program of a poor shell

.gitignore

@@ -4,6 +4,7 @@
 *.exe
 ashwathama
 bash_gitignore.sh
+garibsh
 ior
 pid
 sync

command_executor.c

@@ -0,0 +1,37 @@
+#include<stdio.h>
+#include<unistd.h>
+#include<stdlib.h>
+#include<string.h>
+#include<sys/wait.h>
+
+#define MAXLINE 1000
+
+int main(int argc, char* argv[]) {
+
+   char buf[MAXLINE];
+   pid_t pid;
+   int status;
+
+   while (fgets(buf, MAXLINE, stdin) != NULL) {
+    if (buf[strlen(buf) - 1] == '\n') {
+      buf[strlen(buf) - 1] = 0; /*replace newline with null*/
+    }
+
+    if ((pid = fork()) < 0) {
+      printf("cannot fork\n");
+      exit(1);
+    } else if (pid == 0) {
+      /* child */
+      execlp(buf, buf, (char*) 0);
+      printf("could not execute %s", buf);
+      exit(127);
+    }
+
+    /* parent */
+    if ((pid = waitpid(pid, &status, 0)) < 0) {
+      printf("could not wait\n");
+    }
+   }
+
+   exit(0);
+}

fork.c

@@ -4,8 +4,11 @@
 
 int main(int argc, char *argv[]) {
   if (fork() == 0) {
+    /* child */
     execl("mycopy", "mycopy", argv[1], argv[2], 0);
   }
+
+  /* parent */
   wait((int*)0);
   printf("copy done\n");
   //exit